Manufacture of staple fiber products



J1me 1953 v 1. TAYLOR 2,641,027

MANUFACTURE OF STAPLE FIBER PRODUCTS Filed June 19, 1947 Inventor 34 WImyw/e fagW Attorneys Patented June 9, 1953 MANUFACTURE OF STAPLE FIBER PRODUCTS William Ivan Taylor, Spondon, near Derby, England, assignor to Celanese Corporation of America, a corporation of Delaware Application June 19, 1947, Serial No. 755,629 In Great Britain June 27,1946

4 Claims.

This invention relates to the manufacture of staple fibre products, and particularly to the production of staple fibres from continuous filaments.

The usual method for the production of staple fibre from continuous filaments, having a basis, for example, of regenerated cellulose or cellulose acetate, consists in passing the filaments through a machine which cuts or chops them into short lengths, after which the staple fibres are subjec ed to any other operations, e. g. scutching, carding, drafting and spinning, necessary for their conversion into industrial products.

It has now been discovered that staple fibres can be obtained directly from continuous filaments, and particularly crinkled continuous filaments having a basis of cellulose acetate or other organic derivative of cellulose, by passing them through wool-opening or coarse carding machines such as are used in the preparation of wool for spinning.

According to the present invention, therefore, a method. of converting continuous filaments into staple fibres comprises feeding forward a mass of non-parallel continuous filaments at a controlled speed to a combing point, and combing it onwards from that point at a higher speed, whereby the filaments are torn into staple fibres. The term combing employed herein is not used in the restricted sense in which it is often employed in the textile art and according to which i combing is an operation distinguished from other operations such as opening, scutching and carding, but in a more general sense as meaning the repeated insertion of an array of needle-like or toothlik.e elements laterally into the advancing mass of filaments, and the moving of those elements forward in the direction of travel of the mass but at a greater speed than that at which the mass is fed. The action involved in the method defined above is the action which is exerted in the opening of wool, e. g. by means of a sheeter gill box or of a coarse carding machine. The feeding forward of the mass is effected by the feed rollers of the machine, which grip the mass and feed it slowly forward, while the insertion and moving forward of the teeth is brought about in the former case by the motion of the comb-like fallers of the machine, and in the latter case by the rotation of the roller (the licker-in) which immediately follows the feed roller, and which is clothed with an array of strong projecting teeth. When this action is applied to a mass of non-parallel continuous filaments, the filaments break up into staple fibres having lengths, for example, from 1" to '7". A separate cutting or equivalent operation is unnecessary and the product can be obtained di- 2 rectly in the form of a lap. The staple fibres may be used, if necessary after further conversion operations, as a heat insulating material, as a substitute for eiderdown and similar materials, as a felting material, as a blanket yarn after being spun, or for other purposes.

An advantage of the process is that preliminary operations such as scutching, which are used in the treatment of cotton fibres and in the treatment of staple fibres made by the chopping up of continuous artificial filaments, can be omitted and the staple fibres can be subjected immediately after their production to carding operations. It has further been found that, contrary to what might have been expected, the application of a lubricant or anti-static agent to the filaments before their conversion into staple fibres or before any subsequent carding operation,-

is unnecessary.

The process yields particularly good results when What may be termed direct spun crinkled filaments made of cellulose acetate or other organic derivative of cellulose are employed for the production of the staple fibre. ,Such filaments may be produced by dry-spinning a solution of cellulose acetate or other organic derivative of cellulose in acetone or other volatile solvent using extrusion speeds very much higher than those normally employed, for example extrusion speeds of 700 to 1100 metres per minute, and collecting the extruded filaments without tension. This method of spinning gives springy filaments of a clinging wool-like nature, having for instance- 10 to 15 crinlrles per inch.

Another method by which crinkled filaments suitable for conversion into staple fibre according to the present invention may be produced is that described in U. S. Patent No. 2,431,435, according to which a solution of an organic derivative of cellulose in a volatile solvent mediumv is spun into an evaporative medium, the solution being of low viscosity and at a temperature below the boiling point of the solvent at atmospheric pressure, and the filaments thus obtained are crinkled by treating them with a hot aqueous medium.

For some purposes it is desirable to increase the fire-resistance of staple fibres, and a very suitable method of achieving this is by introducing trichlorethyl phosphate into the fibres, preferably by including it in the spinning solution from which the continuous filaments are produced. For example, the incorporation in a spinning solution of from 5 to 10% of trichlorethyl phosphate, based on the weight of the cellulose acetate or other organic derivative of cellulose present, renders the filaments and staple fibres produced therefrom substantially-non-inflammable, provided that they are not subjected to washing or other operations which extract the trichlorethyl phosphate. This limitation on the use of this substance is not of importance in many cases, since staple fibres employed for heat or sound insulation are not normally subjected to wet treatments.

As stated above, the invention has been found particularly useful in the conversion into staple fibres of crinkled continuous. filaments of cellulose acetate and other organic derivatives of cellulose.

Examples of other organic derivatives of cellulose which may be employed are other cellulose esters such as cellulose propionate and cellulose butyrate, mixed esters such as cellulose acetatepropionate, cellulose acetate-butyrate and cellulose acetate-stearate, and cellulose ethers such as ethyl and benzyl cellulose. While cellulose acetate is the materialpreferred for general pur poses, other cellulose. derivatives may possess particular advantages for particular purposes. Thus, for example, filaments of cellulose acetatestearate may be employed, and give rise to a product which, having a much lower tendency to absorb moisture than a cellulose acetate product, may be preferred as an insulating material for use in situations where it is exposed to dampness. Moreover, continuous filaments, whether crinkled or not, of other materials than cellulose derivatives, e. g. viscose or cuprammonium filaments, may be converted by the method of the present invention from the form of a mass of non-parallel continuous filaments into a staple fibre product.

By way of example one method of producing direct spun crinkled filaments, and two methods of converting the filaments so produced into a staple. fibre lap, will now be described in greater detail with reference to the accompanying drawings in. which:

Fig. l is a diagrammaticv side elevation of a spinning cell for the production. by extrusion of the direct spun crinkled filaments,

Fig. 2 is a diagrammatic side elevation of a coarse carding machine of the teaser or Fearnought type adapted for the conversion of continuous filaments into staple fibres,

Fig. 3 is a side elevation of a sheeter gill-box adapted for the same purpose, and

Fig. 4 is a diagrammatic side elevation of a roller-carding machine for the further treatment of the staple fibre lap produced by the machine in Fig. 3.

Referring, to Fig. 1, the spinning cell I is supplied with air through an inlet 2 near the bottom of the cell, the air being extracted near the top of the cell by a draw-off device 3 leading to a suction header 4. The air in the cell is heated by means of steam pipes 5. cell is a compartment 6 filled with heating liquid and containing a filter candle specially adapted for the heating of the spinning solution passing through it by heat transfer from the heating liquid. After passingthrough the candle l the spinning solution is extruded through a spinning jet 8 disposed in the top of the cell l, the filaments 9 so extruded falling to the bottom of the cell and collecting as a mass l which is removed at intervals through a door H in the back of the cell.

The spinning solution. employed is a solution of cellulose acetate in acetone of about 26 concentration and emerges. from the spinning orifices in. the jet 8 at a linear speed ranging from At the. top of the 700-1100 metres per minute depending upon the size of the jet holes which, for the speeds mentioned may rangefrom 0.05 to, 0.10 mm. diameter. The pressure behind the jet is adjustedto give an extrusion speed appropriate to the size of the orifice, the lower speeds corresponding to the smaller orifices. This method of spinning gives springy filaments of a clinging wool-like nature having crinkles along their length of a frequency of 10-15 per inch. The spinning solution is heated, while passing through the filter candle! in the chamber 6, to a temperature of about 60 C., while the cabinet temperature is maintained a few degrees lower.

If desired, in order to improve the fire-resisting properties of the final product, the spinning solution may have: added to it trichlorethyl phosphate in the. proportion of 7 /2 on the weight of the cellulose acetate in the solution. Since the addition of this fire-proofing agent tends to make the filaments slightly tacky, the cabinet temperature is preferably increased to about 70 in order to increase the drying effect of the air passing through the cell and to avoid a. tendency for filaments to stick together in the mass I0 formed at the bottom of the cell.

The mass In is removed at intervals through the door I! in the bottom of the cell and con veyed in sacks to the machine by which the continuous filaments thereof are converted into staple fibres. This may be done in one stage on a coarse carding machine of the kind diagrammatically shown in Fig. 2,. In this machine the filaments are spread by hand on a lattice l5 by which they arev conducted to the feed rollers of the machine which feed them, as a mass of nonparallel continuous filaments, to the coarse teeth of the licker-in cylinder. This rotates with a higher peripheral speed than that at which the continuous filament mass is fed by the feed rollers and, accordingly, the Strong coarse teeth of the machine break up. the continuous filaments into staple. fibres. In their progress through the machine the staple fibres are to some extent straightened and parallelised by the action of the main swift (whose axis is indicated at l6) and of the worker and clearer cylinders (whose axes are indicated at IT). A dofier cylinder it re.- moves the fibres from the main. swift and feeds them forward to a collecting drum i9 as a thin continuous sheet of fibres. The sheet of fibres is collected on the drum l9 until. a sufiieient thickness 20 of material has accumulated thereon, whereupon the material is out from the drum in the form of a sheet or lap- Instead of carrying out the conversion in a single step, as described above with reference. to Fig. 2, it may be done in two or more steps. Thus the mass of fibres l0 produced as shown in Fig. 1, may be conveyed to av sheeter gill box of the kind diagrammatically illustrated in Fig.3. Here the continuous. filament mass is spread out over the feed lattice at. the feeding end 22 of the. machine which conducts it to feed rollers which, cooperating with the faller teeth of the machine. convert the. mass into stapl fibres. The staple fibre mass, somewhat parallelised by the action of the faller teeth and of the delivery rollers, collects on an apron 2.5 cooperating with a further apron 26: and: with edge discs 2:1. The fibres. are allowed to accumulate on the apron 25 until they form a layer. about 1 to 1 /2 inches thick when they are cut off in the form of a. crudev lap about 18 inches in width and about; 7 feet. in length. The crude laps are conveyed. tcv a roller card machine of the kind shown in Fig. 4 in which such laps are fed two abreast (preferably in staggered relation) to the feed lattice 30 of the machine, are combed and parallelised in their passage through the machine and are removed from the doffer cylinder 3| of the machine by means of a doifer knife 32. The resulting thin sheet 33 of staple fibres proceeds to a collecting drum 30 about 24" in diameter and 40 in length. The drum is driven at a speed of 5 revolutions per minute and the collection of the sheet of fibres 3S thereon is continued until a sumcient thickness is obtained. Thus by continuing the collection for about 30 minutes a lap of 3 inches in thickness is obtained, having 150 layers of the thin sheet of fibres 33.

Laps made of staple fibres produced as described above have a low apparent density of, for example, 1 to 2 lbs. per cubic foot, are springy and have a good recovery from pressure. The fibres hold together well and the laps can be roughly handled without the fibres falling out. If desired, however the laps may be given greater rigidity by the application of a suitable adhesive thereto, e. g. a solution of methyl cellulose or of a natural or artificial resinous material such as a co-polymer of vinyl chloride and vinyl acetate. Thus, the drum [9 of Fig. 2 or the drum 34 of Fig. 4 may be sprayed during the formation of the lap 20 or collection of the sheet of fibres thereon, with a 0.75% aqueous solution of methyl cellulose, the spraying being effected, by hand or otherwise, with a spray gun supplied with air at 45 lbs. per square inch pressure. A suitable quantity of adhesive to apply is about 1 on the weight of the fibres. To facilitate uniform distribution of the spray, a water-soluble dye may be added to the solution. Moreover, the solution may contain a plasticiser for the adhesive in order to render the adhesive more flexible and to promote adhesion.

Instead of using the staple fibres in lap formation they may be subjected to further operations by which they are converted into other forms, e. g. to convert them into spun yarn. Mixed yarns containing staple fibres produced according to the process of the present invention and other fibres, e. g. wool fibres, may be produced by mixing the staple fibres with such other fibres at a suitable stage in the manufacture of the yarn, or such other fibres may be fed, together with the continuous filaments, to the machine in which production of the staple fibres is effected.

Having described my invention, what I desire to secure by Letters Patent is:

1. Method of converting continuous filaments into staple fibres, which comprises feeding forward a mass of randomly oriented continuous filaments at a controlled speed to a combing point, combing the mass onwards from that point at a higher speed whereby the filaments are torn into staple fibres and formed into a sheet of said fibres, rolling said sheet on the surface of a rotating cylinder to form thereon a thick layer of staple fibres, said thick layer being of a width substantially equal to the width of said sheet of staple fibres being taken up on said rotating cylinder, and cutting said layer from the cylinder in the form of a fiat lap.

2. Method of converting continuous filaments into staple fibres, which comprises feeding forward a mass of randomly oriented continuous filaments at a controlled speed to a combing point, combing the mass onwards from that oint at a higher speed whereby the filaments are torn into staple fibres and formed into a sheet of staple fibres, rolling said sheet on the surface of a rotating cylinder to form thereon a thick layer of staple fibres, said thick layer being of a width substantially equal to the width of said sheet of staple fibres being taken up on said rotating cylinder, spraying said sheet with a solution of an adhesive as it is wound on to the cylinder to improve the cohesion of said layer, and cutting said layer from the cylinder in the form of a flat lap.

3. Method of forming a coherent product having a basis of staple fibres, which comprises freely extruding a solution of cellulose acetate, together with a fire-proofing plasticizer therefore, in acetone into an evaporative atmosphere at a high velocity so as to form continuous crinkled filaments of cellulose acetate, collecting said filaments without tension into a mass of randomly oriented continuous filaments, feeding forward said mass at a controlled speed, gilling the mass as it is so fed whereby the filaments are torn into staple fibres, subsequently carding the staple fibre product so produced into a sheet, rolling said sheet on the surface of a rotating cylinder to form thereon a thick layer of staple fibres, said thick layer being of a width substantially equal to the width of said sheet of staple fibres being taken up on said rotating cylinder, spraying said sheet as it is rolled with a solution of an adhesive to improve the cohesion of said layer, and cutting said layer from the cylinder in the form of a fiat lap.

4. Method of forming a coherent product having a basis of staple fibres, which comprises freely extruding a solution of cellulose acetate. together with a fire-proofing plasticizer therefor, in acetone into an evaporative atmosphere at a high velocity so as to form continuous crinkled filaments of cellulose acetate, collecting said filaments without tension into a mass of randomly oriented continuous filaments, feeding forward said mass at a controlled speed, subjecting the mass as it is fed forward to a coarse carding operation at the outset of which the filaments are combed onwards at a higher speed and are thereby torn into staple fibres and in the course of which the fibres are formed into a sheet of staple fibres, rolling said sheet on the surface of a rotating cylinder to form thereon a thick layer of staple fibres, said thick layer being of a width substantially equal to the width of said sheet of staple fibres being taken up on said rotating cylinder, spraying said sheet as it is rolled with a solution of an adhesive to improve the cohesion of said layer, and cutting said layer from the cylinder in the form of a fiat lap.

WILLIAM IVAN TAYLOR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,883,424 Taylor Oct. 18, 1932 2,088,642 Dreyfus July 3, 1937 2,180,172 Schmitt Nov. 14, 1939 2,338,610 Wiley Jan. 4, 1944 2,410,307 Rumsey Oct. 29, 1946 2,416,390 Hitt Feb. 25, 1947 FOREIGN PATENTS Number Country Date 29,030 Great Britain of 1911 450,963 Great Britain July 27, 1936 473,569 Great Britain Oct. 15, 1937 750,978 France Aug. 24, 1933 

